The primary purpose of the proposed research is to extend the longitudinal behavioral genetic study of aging known as SATSA (The Swedish Adoption/Twin Study of Aging) with a longitudinal follow-up 12 years after the initial in-person testing of 480 individuals from approximately 350 twin pairs, allowing for up to 4 times of in-person testing per subject. The point at which any participant shows onset of cognitive impairment or dementia as well as mortality information will be linked to the dataset. Of principal interest is research question 1) What are genetic and environmental contributions to individual differences in long-term change and continuity late in life with respect to measures of cognition, personality and well being, functional health (including performance activities of daily living), physical health (including measured biomarkers), and health- related behavior? Additional research questions include 2) Do patterns of change reflect cohort or aging effects? The cross-sequential design across up to four measurement occasions will now allow analyses to address this issue. 3) What factors influence onset of significant cognitive decline? Do influences on normal cognitive decline differ from those factors that influence onset of dementia? 4) Do telomere length, anti- oxidative capacity, and APO-E genotype represent genetic susceptibility markers for cognitive decline? What role do environmental effects play in the associations between these susceptibility markers and cognitive decline? 5) Is there a terminal decline pattern discernable and to what extent does the relationship reflect mediation by a shared set of genetic and/or environmental factors? 6) What is the nature of the pattern of short-term, lagged covariances in traits purported to be relatively stable? Are individual differences in amounts of short-term intraindividual variability concordant in twins? 7) To what extent do genetic and environmental factors mediate the relationship between health and well-being in the elderly? The explication of individual differences in aging has basic research implications for increased understanding of the fundamental processes of normal and pathological aging, as well as applied implications for treating disorder, preventing disease, and optimizing quality of life.